This invention relates to electrical contacts and methods of manufacture
The invention is more particularly concerned with hyperboloid socket contacts and their manufacture.
Hyperboloid socket contacts have a number of resilient wires extending longitudinally of the socket with opposite ends of the wires displaced with respect to one another through a small angle around the circumference of the socket so that the internal diameter of the passage through the wires midway along the length of the socket is reduced. This forms a resilient contact region for a male pin contact inserted in the socket. Opposite ends of the wires are welded to some form of retaining structure. Typically, a socket might have five wires equally spaced from one another around the circumference of the socket. The contacts are usually made by loading individual wires into respective slots in a cylindrical mandrel, the slots extending along the mandrel at an angle. The mandrel holds the wires in position while their ends are welded to some form of retaining structure. Contacts of this kind are described, for example, in U.S. Pat. Nos. 3,023,789, 3,107,966, 3,470,527, 3,557,428, and 5,203,813. Hyperboloid contacts are sold by Hypertac Limited of London, England, by Hypertronics Inc of Hudson, Mass., USA and by Interconnectron GmbH of Deggendorf, Germany.
Hyperboloid contacts have various advantages over other contacts in that they can have a low contact resistance, a low insertion force, a long effective life, they can carry high currents, they have an excellent wiping action and can be stable under shock and vibration.
It is an object of the present invention to provide an alternative contact and method of manufacture.
According to one aspect of the present invention there is provided an electrical socket having a retaining structure and a plurality of resilient wires extending along the socket in a hyperboloid arrangement and exposed for contact with a male contact member inserted within the socket, the wires being arranged in groups of at least two wires each, and the spacing of the wires in each group being closer than that of the groups from one another.
The wires in each group preferably extend along the socket in contact with one another. The socket may include three groups of two wires each. The wires may be retained in groups by attachment to rings at opposite ends of the socket.
According to another aspect of the present invention there is provided a method of making an electrical socket comprising the steps of loading at least two spring wires into each of a plurality of slots in a mandrel, which slots extend along the mandrel at an angle to its axis, inserting the mandrel with the loaded wires into a retaining structure, attaching opposite ends of the wires to the retaining structure, and removing the mandrel to leave the wires extending along the socket in a hyperboloid arrangement.
The at least two wires are preferably loaded into the respective slots in the mandrel at the same time. The retaining structure may include a ring at opposite ends of the socket to which the wires are attached. The wires may be attached to the retaining structure by welding.
According to a further aspect of the present invention there is provided an electrical socket made by the method of the above other aspect of the invention.
A socket and its method of manufacture, according to the present invention, will now be described, by way of example, with reference to the accompanying drawings.